Author: UrsFormat: MarkdownItexI have also added statement and proof of the expression as a contour integral: now the last item [here](https://ncatlab.org/nlab/show/causal+propagator#EquivalentExpressinsForCausalPropagatorOnMinkowskiSpacetime)
(All these formulas suffer from prefactor ambiguities due to various possible different conventions and due to the computations being prone to prefactor errors. I am trying to be self-consistent, but I won't be surprised if there are prefactor errors left. But once I am through with this and related entries, I'l go through them all once more and will streamline them.)

I have also added statement and proof of the expression as a contour integral: now the last item here

(All these formulas suffer from prefactor ambiguities due to various possible different conventions and due to the computations being prone to prefactor errors. I am trying to be self-consistent, but I won’t be surprised if there are prefactor errors left. But once I am through with this and related entries, I’l go through them all once more and will streamline them.)

Author: UrsFormat: MarkdownItexI believe I have now compiled complete proof of the wave front sets of the causal, Hadamard and Feynman propagator on Minkowski spacetime, [here](https://ncatlab.org/nlab/show/causal+propagator#WaveFrontSetsOfPropagatorsForKleinGordonOperatorOnMinkowskiSpacetime).

I believe I have now compiled complete proof of the wave front sets of the causal, Hadamard and Feynman propagator on Minkowski spacetime, here.